1. Field of the Invention
The invention relates to a structure of a display device using a polarizer.
2. Description of the Related Art
In recent years, a so-called flat panel display, which is a display device that is very thin and lightweight as compared to the conventional cathode-ray tube display device, has been developed. A liquid crystal display device including a liquid crystal element as a display element, a light-emitting device including a self-light-emitting element, an FED (field emission display) using an electron beam, and the like compete in the market of flat panel displays. Therefore, lower power consumption and higher contrast ratio are demanded to increase the added value so as to differentiate from other products.
In general, in a liquid crystal display device, each substrate of a pair of substrates is provided with one polarizing plate to maintain a contrast ratio. When display of darker black is performed, the contrast ratio can be enhanced accordingly. Thus, higher display quality can be provided when an image is seen in a dark room such as a home theater room.
For example, in order to reduce display non-uniformity caused by shortage of polarization degree and polarization distribution of polarizing plates and to improve a contrast ratio, a structure is suggested in which a first polarizing plate is provided outside a substrate on a viewing side of a liquid crystal cell, a second polarizing plate is provided outside a substrate on a side opposite to the viewing side, and a third polarizing plate is provided for increasing the degree of polarization when light from an auxiliary light source provided on the substrate side opposite to the viewing side is polarized through the second polarizing plate and transmitted through the liquid crystal cell (see Reference 1: PCT International Publication No. 00/34821).